The long-term objective of this proposal is to contribute to the Biliary Atresia Research Consortium to assure its success in improving the understanding of the etiology, pathogenesis, and disease mechanisms of biliary atresia and improving the clinical care, diagnosis and management of affected children. This is an important project because biliary atresia affects about 600 children each year in the US. Its cause is unknown. There are no good studies regarding early diagnosis or screening strategies, which are needed to improve patient care. The medical and surgical care of affected children is sub-optimal. Biliary atresia is the number one indication for pediatric liver transplantation, accounting for about 50% of cases in the US. The cost of care of this relatively rare disease is exorbitant. Better understanding of the disease should lead to improved care, better outcomes and reduced cost of care. The specific aims of this proposal are #1 To participate fully as a clinical center in the Biliary Atresia Clinical Research Consortium. This entails participation in the development of the functions of the consortium, including determining data to be collected, projects to be undertaken and how information is to be disseminated; #2 To identify and enter into the consortium database all or nearly all of the cases of biliary atresia in the upper mid-west region over the five year period of the grant to determine the incidence of the disease and important epidemiological characteristics, such as racial/ethnic, socioeconomic and gender differences in incidence, secular trends, and temporal relationship to identifiable viral epidemics; #3 To examine prognostic indicators in a select cohort of biliary atresia patients.; and #4 To examine the hypothesis that biliary atresia is a viral-induced, immune mediated disease.